John Deere 1867 – RCU: RPM Micro Power Supply Failure

The Reverser Control Unit (RCU) attempted to send low-amperage power to the RPM module on circuit cc# 302, but detected that the power-on command was unsuccessful. This indicates a failure in the activation or operation of the RPM micro power, which could be caused by an open circuit, a faulty RPM module, or an internal failure within the RCU itself.

• 9570 STS
• 9670 STS
• 9770 STS
• 9870 STS
• 7210
• 7410
• 7510
• 7610
• 7710
• 7810

1. 1

   Verify the fault code on the machine's display and note if it is active or stored

2. 2

   Cycle power by completely shutting down and restarting the machine to see if the fault clears

3. 3

   Visually inspect the wiring harness and connectors between the RCU and RPM module/speed sensors for damage, corrosion, or loose connections

4. 4

   Check for other active fault codes that might indicate broader electrical issues like low system voltage or communication errors

1. 1

   Isolate the fault

   Use diagnostic tests to determine if the fault lies with the RCU, the RPM module, or the wiring between them.

2. 2

   Test components and wiring

   Test for continuity and voltage at the RCU and RPM module connectors to verify that power is being sent and received correctly.

3. 3

   Repair or replace components

   Repair or replace damaged wiring. If wiring is intact, replace the faulty RPM module or the Reverser Control Unit (RCU) based on the voltage test results.